Three of the Obama administration’s appointments to the National Labor Relations Board, for some time, were invalid, the Supreme Court ruled unanimously today, because they bypassed the Senate as “recess appointments” while the Senate actually was in session.

The result came in NLRB v. Noel Canning et al., a case in which Canning, a businessman, challenged an NLRB on the grounds that the board didn’t have a quorum, because three appointments had been invalid. The Court’s opinion was written by liberal justice Stephen Breyer.

The White House made the appointments in January 2012 via the Constitution’s recess-appointment power, which allows the executive branch to make appointments without confirmation by the Senate when the legislature is in recess. But the appointments were made when the Senate was, practically speaking, in recess, but was holding pro forma sessions. Essentially, the Court ruled, the White House usurped the Senate’s powers to determine its own rules and sessions.

Both the House and the Senate, the Court ruled, have the power to call pro forma Senate sessions, during which the president can’t make recess appointments.

What exactly happens to the NLRB decisions made by the board populated with invalid members isn’t clear.

The Court did rule 5–4 against upholding the decision of the D.C. Circuit Court of Appeals, which had reached a much stricter vision of recess-appointment powers — that the president could only use them when an appointment opened up during a recess, rather than for any position that remained open during a recess. The majority opinion held that there is long historical precedent for the idea the vacancies the Constitution says can be filled via recess appointments — “vacancies that may happen during the recess of the Senate” — include those that were open before the recess began.